This is what a 150 watt per channel amplifier would really look like. It weighs 90 pounds and requires its own dedicated 20A outlet on AC!!!!!!:
This is what a "chip amp" looks like. They are found in most automotive & marine in-dash stereos. It is about the size of a quarter and weighs about the same as a dime.
400 Watts from a car deck ? :Liar::Liar::Liar::Liar: Yep saw it in the aisle of Wal*Mart...

Only if they're egregiously lying about it... Those numbers you see on the boxes and fronts of car/marine stereos are most often very, very heavily "massaged" numbers taking one specific easy to drive frequency at a horrible THD distortion level and even then likely rating a split second peak to trough.
They have other sneaky ways of rating them too, like the "W" does not even mean watts but 400 "wow" factor and some other bogus shenanigans. Phil is SPOT ON about this and the real expert on this subject. Most car stereos have more like 4-8 listenable WPC at best at 12.3 - 12.7V and perhaps, at best, up to 9-11 at 14.6V...
Car audio companies are among the most misleading of any consumer brands when it comes to marketing claims, but they get away with it because the industry is rather lax and few want to self regulate. The ones who are honest, lose sales to the liars, so they all seem to choose to mislead....
To be fair here is a 100 WPC car amplifier (at car audio "quality") with only somewhat misleading specs and decent sound quality. It will set you back about $2200.00... This amp is 3" Tall x 12.5" Wide x 18.4" Long and will draw upwards of 50A DC. It draws about 2.5A DC just sitting there at idle doing NOTHING.......
If you want a unit that is more fairly rated, still not a fool proof standard, buy one that says: "Amplifier Power Standard CEA-2006 Compliant." Keep in mind though that this power rating is at 1.0% THD and 14.4V. A 1.0% THD is HORRIBLE and in the ear bleeding range especially when you consider that it is not rated at 20 Hz to 20 kHz and they've likely picked a "favorable" frequency to rate it at. They are usually way worse than 1% THD if they were accurately rated from 20 Hz to 20 kHz as an audiophile grade amp would be..
My old amp was rated at 0.04% @ 20 Hz to 20 kHz.. This is in the range of barely even audible across the entire frequency range but it took 90 pounds of weight and a dedicated 20A outlet to get there even at 120V..
On a sailboat you're rarely at 14.4V, and 1% THD is a pretty poor level of distortion as far as sound "quality"... I would bet it is pretty hard finding ANY CAR OR MARINE DECK (not an external amplifier) that has a CEA-2006 "amplifier" rating. I don't recall ever seeing one. Manufacturers only tend to rate EXTERNAL AMPS, not in-dash decks. I guess they don't rate decks so they can lie to you in the aisles of Wal*Mart and Best Buy.
I found this a long while ago and it makes for some interesting reading..
Outrageous Audio Claims
You're not going to find in-dash "deck power" in any car or marine stereo with a real 50W, 100W, 200W or the 400W that many of them claim. At least not that meets CEA standards or any "reputable" method of testing output, but, you can find PLENTY of liars...
Yes, you CAN find an external amplifier that puts out 50WPC but it will suck your bank like a Vampire sucks blood. A quick glance at the McIntosh amp above and its 50A DC current capability should solidify what it takes to produce a real 100WPC in a 12V amplifier. It really puts the "bogus" 240WPC in-dash stereo in perspective..
As seen below 1.4A can render a very "listenable" level. With our Kenwood Excelon deck but we have efficient speakers and two in the cockpit and two in the salon.
This is two channels driven, 4 Ohm nominal speakers w/92 SPL "rated" efficiency, white noise CD @ 1.62A and 103dB.
It sounds like crap pushing 103dB and is LOADED with distortion but it can do it...
My only point is that I don't want people to assume they are going to be drawing 8-20A through a car type deck... They draw very little at decent listening levels....
I had a customer who was concerned about it and wanted to buy a Fusion stereo. I made this video for him. As you can see with the stereo clipping (distorting heavily), and this was at 14.2V BTW, it was drawing just 1.5 +/- amps...
BTW This unit is rated at 280 Watts or 4X70 WPC. Hmmm 1.5A at clipping??????
http://www.youtube.com/watch?v=_u0lKKWlX1I
As others have said .75A to 2A is what most car stereos will draw on boats...
Yes, I am passionate about that subject and it goes back to my good friend who is a musician, and who LOVES music. Unknown to me he went four years without using his on-board stereo because it said 400W on the front of it and he did not want to kill his bank. Without a battery monitor he just assumed the 400W to be true. Once I showed him it drew 0.5A to 2.2A he was a VERY happy camper and is still listening to music on-board to this day...
I just get frustrated that manufacturers are allowed to BLATANTLY lie, and get away with it. It is simply not fair to the consumer. This is done in the vitamin supplement industry, electronics industry and many others and it is just "accepted". :cussing:
What if the airlines were allowed to BLATANTLY lie about safety and maintenance schedules, with no data or FAA oversight to keep checks and balances better in-line? I don't want to go there, but with "neutraceuticals" (vitamin & supplements) and "electronics" we just accept it...
Trust me I am NOT for any more government "intervention", as we all know how that goes, I just want some semblance of honesty that is COMPLETELY lacking in car & marine stereos.
The lies in the electronics & neutraceuticals industries have become so egregious that it does not even resemble anything even close to the truth. Sadly every year people spend hundreds of millions on one stereo over another because one manufacturer told a bigger lie than the next. They also spend hundreds of millions on neutraceuticals because company "A" told me I'd cure cancer and my manhood would grow 6 inches....
Fair to the US consumer...? Hardly....
End rant...